hadoop2.7.3 Windows eclipse开发环境搭建及WordCount实例运行

一、准备工作

● eclipse-jee-luna-SR2-win32-x86_64
● hadoop-eclipse-plugin-2.7.3.jar
● hadoop-2.7.3.tar.gz
● hadoop.dll、winutils.exe

二、eclipse添加hadoop插件

将下载的hadoop-eclipse-plugin-2.7.3.jar拷贝到eclipse的dropins或plugins目录中，重启eclipse即可看到左上角的DFS Locations。

三、配置DFS Location

从Window->show view->other中选择调出，新建一个DFS Location

点击finish，即可浏览新增加hdfs location中的文件

四、运行环境配置

1. 新建HADOOP_HOME环境变量

1. 在PATH中增加%HADOOP_HOME%/bin

1. 将下载的hadoop.dll、winutils.exe拷贝到%HADOOP_HOME%/bin目录下

五、新建Map/Reduce Project——WordCount

import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;public class WordCount {    public static class WordCountMapper extends Mapper<Object, Text, Text, IntWritable> {        private final static IntWritable one = new IntWritable(1);        private Text word = new Text();        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {            StringTokenizer itr = new StringTokenizer(value.toString());            while (itr.hasMoreTokens()) {                word.set(itr.nextToken());                context.write(word, one);            }        }    }    public static class WordCountReducer extends Reducer<Text, IntWritable, Text, IntWritable> {        private IntWritable result = new IntWritable();        public void reduce(Text key, Iterable<IntWritable> values, Context context)                throws IOException, InterruptedException {            int sum = 0;            for (IntWritable val : values) {                sum += val.get();            }            result.set(sum);            context.write(key, result);        }    }    public static void main(String[] args) throws Exception {        Configuration conf = new Configuration();        if (args.length != 2) {            System.err.println("Usage: <in> <out>");            System.exit(2);        }        Job job = Job.getInstance(conf, "word count");        job.setJarByClass(WordCount.class);        job.setMapperClass(WordCountMapper.class);        job.setCombinerClass(WordCountReducer.class);        job.setReducerClass(WordCountReducer.class);        job.setOutputKeyClass(Text.class);        job.setOutputValueClass(IntWritable.class);        FileInputFormat.addInputPath(job, new Path(args[0]));        FileOutputFormat.setOutputPath(job, new Path(args[1]));        System.exit(job.waitForCompletion(true) ? 0 : 1);    }}

六、配置运行参数

在hdfs中新建一个tmp目录：hadoop fs -mkdir /tmp
修改目录权限：hadoop fs -chmod -R 777 /tmp

在本地新建一个文件input01，输入：
hello world
hello china
hello jiangsu
hello suzhou

配置Run Configurations

七、运行程序

运行结果如下：